D43. New Paradigms in Rejection Monitoring: Lymphocyte Subsets as Non-invasive Graft Markers in Face Transplantation

PURPOSE: In the evolving field of vascularized composite allotransplantation (VCA), face transplantation stands as a transformative intervention for disfigured patients. Monitoring of graft rejection, however, remains a critical challenge. This study aims to investigate the role of lymphocyte subsets in the early detection and monitoring of graft rejection in face transplantation. We seek to establish a biomarker profile for confirming rejection, thereby enhancing patient outcomes and graft longevity. METHODS: We conducted a retrospective chart review of three face transplant recipients who underwent face transplantation at our institution. Peripheral blood samples were analyzed for lymphocyte subsets at multiple time points post-transplantation. A linear mixed-effects model was employed, aiming to identify any upregulation associated with episodes of graft rejection. RESULTS: A statistically significant relationship was found between clinically treated episodes of rejection, ultimately confirmed by histology, and several lymphocytic subsets. CD3+ and CD3+CD4+ cell lineages were found to be significantly upregulated during times of rejection (p=.0147 and p=.0153, respectively). Furthermore, CD3+CD8+ and CD16 + 56+ cell lineages were also found to be significantly associated with rejection (p=.0490 and p=.0019, respectively). Further stratification with postoperative day as a random effector demonstrated that CD16 + 56+ cell lineages remained significantly upregulated during episodes of rejection (p=.0358). CONCLUSION: Our study demonstrates that monitoring specific lymphocyte subsets offers a promising adjunct for graft surveillance that is a less invasive when compared to traditionally employed punch biopsies. This approach not only enhances the precision of rejection monitoring but also improves patient comfort and compliance, thereby contributing to better long-term graft outcomes.